Rolling method and a rolling mill for carrying out the method

ABSTRACT

A rolling method for producing a semi-finished metal section from a larger metal section of substantially rectangular crosssection and with which the width of two opposing, first sides exceeds the width of the remaining two, second sides. The metal section is reduced by reversable rolling without being turned around its long axis in several passes between two working rolls which are capable of being progressively urged towards said second sides of the metal section. The metal section is guided during the reduction process into and out of the roll nip and the original distance between said first sides of the metal section is maintained constant during the entire rolling sequence by means of two pairs of guide rolls arranged on either side of the working rolls, the guide rolls having smooth barrel surfaces and presenting a nip of constant width therebetween and having a diameter which is considerably smaller than that of the working roll.

[ Nov. 19, 1974 United States Patent [191 I Strandell [57] ABSTRACT Arolling method for producing a semi-finished metal ROLLING METHOD AND AROLLING MILL FOR CARRYING OUT THE METHOD [75] Inventor: pebolof Srande,Taby Sweden section from a larger metal section of substantiallyrectangular cross-section and with which the width of AB Metalfol'm,Stockholm two opposing, first sides exceeds the width of the re- 6, 1972maining two, second sides. The metal section is reduced by reversablerolling without bein PP 9101303342 around its long axis in severalSweden [73] Assignee:

[22] Filed:

g turned passes between two working rolls which are capable of bein gprogressively 52 US. 72 199, 72 366 urged towards Said Second Sides ofthe metal Section- 1 The metal section is guided during the reductioncess into and out of the roll n pro- [51] Int. B21b 1/00 72/199, 229,225, 366,

ip and the original dis- [58] Field of sea iiiiiiiiiiiiji' 72/250.29/527] tance between said first sides of the metal section ismaintained constant during the entire rolling sequence by means of twopairs of guide rolls arranged on either side of the working rolls, theguide rolls having smooth S T m I N m m E m .m d m mm 9A" "I. up. C "U"S NR S H 9 r. H W Te nAnt e fio rTal .mS BHSK e D 1113 3777 9999 NHHHH 659 2526 5935 8707 m 0585 5 ,5] 333 vmd M m mC S m-l h] n .1 O m S f r.mwe .1 .Wmm F m m .1e m m m ta Ta D a m 3 v mam S d n nda h mmum C e r 6mo th e mwm SBS .lby mwN m w b. ..e 5796 2396 22 3 2222 7777 PrimaryExaminer-Milton S. Mehr Attorney, Agen1,or FirmStevens, Davis, Miller &Mosher PATENTEB NEW] 9 I974 SHEET 10F 2 ROLLING METHOD AND A ROLLINGMILL FOR CARRYING OUT THE METHOD The present invention relates to anovel hot rolling method for producing a semi-finished metal sectionfrom a larger metal section of substantially rectangular cross-sectionand with which the width of two opposing, first sides exceeds the widthof the remaining two, second sides. The invention also relates to arolling mill for carrying out the novel method.

Semi-finished metal sections which are to be subjected to further metalshaping processes, such as rolling or forging processes, are normallyproduced by reducing an essentially square, large metal section, such asan ingot, to a square metal section of smaller crosssectional area. Witha conventionally applied method, semi-finished metal sections areproduced by reducing an ingot of square cross-section, having sidesapproximately 500 mm in width, to square sections whose sides have awidth of from 80 to 100 mm. Rolling is carried out in a reversibletwo-high mill provided with grooved rolls. The grooves are several innumber and are arranged in series of decreasing cross-sectional area.The metal section, subsequent to having been reduced in one or morepasses through a groove of large crosssectional area is transferred to agroove of smaller cross-sectional area and further reduced therein.Between every second or fourth pass through the rolls, the section isturned 90 around its long axis. Despite the fact that several passes canbe made through the same roll groove, this method of reducing metalsections necessitates the provision of a plurality of grooves, which inturn requires a long roll barrel in order for all the necessary groovesto be accomodated. Because the roller conveyor paths by which the metalsection is moved on both sides of the rolling mill must have a widthcorresponding to the barrel length, a long barrel consequentlynecessitates a wide roller path, which renders such paths heavy andexpensive. The same is also true of the guide means used for lateralmovement of the metal section on the roller paths from one groove toanother. The rolling operation and apparatus connected therewith arefurther complicated by the turning hooks or like devices which must beused to turn the metal section around its long axis. The entire rollingmill thus large, heavy, relatively complicated, extremely bulky andexpensive. Similar disadvantages are also found with rolling mills forreducing or finish-rolling prerolled sections.

The technique of forming metal sections by continuous casting methodshas expanded rapidly over recent years. This technique is appliedconventionally for continuously casting metal sections of squarecross-section as starting material for other metal working processes,such as the manufacture of rod and wire material. Instead of castingsections of square cross-section, it is, however, desirable to castmetal sections of rectangular cross section, where the depth orthickness of the section is small in relation to the width, since withmetal sections of this configuration the casting speed can be increasedand the production rate of the continuous casting plant consequentlyraised. Owing to the lack of a suitable rolling method and rolling mill,metal sections having a rectangular cross-section can only be workedinto metal sheet.

An object of the present invention is therefore to provide a rollingmethod with which ingots and other metal sections of substantiallyrectangular cross section with which the width of two opposing firstsides, hereinafter called the broad sides, exceeds the width of the tworemaining second sides, hereinafter called the edge sides, can bereduced to sections of essentially rectangular cross section and ofsubstantially any desired relationship between the width and the depthof the metal section, in a particularly simple and practical manner andwith the use of constructionally simple means. A further and specialobject of the invention is to provide a method by means of which aningot or other metal sec tion of small thickness in relation to thewidth can be rolled to a metal section of square cross-section, thewidth of the sides of which is substantially equal to said thickness, orof rectangular cross-section where two opposing sides each have a widthsubstantially equal to said width and where the width of each of theremaining two, opposing sides is smaller than said width.

For the purpose of achieving these objects, it is proposed in accordancewith the invention that, when practicing a rolling method of the typereferred to in the preamble to the description, the metal section isreduced by reversable rolling techniques without being turned around itslong axis, in several passes between two working rolls which are capableof being progressively urged towards said second sides of the metalsection, and that the metal section is guided during the reductionprocess into and out of the roll nip, and that the original distancebetween said first sides of the metal section is maintained constantduring the entire rolling sequence by means of two pairs of guide rollsarranged on either side of the working rolls, the guide rolls havingsmooth barrel surfaces and presenting a nip of constant widththerebetween and a diameter which is considerably smaller than that ofthe working rolls.

When practicing the method of the present invention in connection withcontinuous casting techniques where the casting has an elongatecross-section, the casting is first cut into sections of suitable lengthand the sections rolled to the desired shape and size, optionally afteradjusting the temperature of the sections to a magnitude suitable forhot rolling purposes. The method of the present invention is thustotally independent of the rate at which the casting is formed.

Another object of the present invention is to provide a rolling millwhich is not encumbered with the aforementioned disadvantages and whichcan be used for practicing the novel method of the invention. For thepurpose of achieving this latter object, there is provided in accordancewith the invention a rolling mill for producing a semi-finished metalsection from a metal section having a substantially rectangularcross-section and with which the width of two opposing first sidesexceeds the width of the two second sides, the rolling mill beingcharacterized in that it comprises three pairs of rolls arranged in astraight line in a juxtaposed relationship in a common frame structure,the central pair of rolls comprising a pair of reversably drivableworking rolls which can be adjusted to vary the nip therebetween andwhich are capable of being applied to said second sides of themetal-section to be reduced. The two remaining roll pairs, hereinaftercalled the guide roll pairs, have a smooth roll surface and a facelength which considerably exceeds the face length of the pair of workingrolls and the nip present between co-acting rolls extends at rightangles to the roll nip of the working roll pair, while the width of thenip of the working rolls is pre-set in a manner such as to coincide withthe width of said second sides, i.e. the edge sides, of the metalsection, to be reduced. The rolling mill of the present invention isextremely compact andrequires but little space, and is also much lighterand cheaper and requires much simpler and less expensive operatingequipment than conventional rolling mills. The rolling mill of thepresent invention is therefore also suited for low-capacity steel andmetal works, for which conventional rolling mills are uneconomical, andprovides at the same time considerably increased selectivity withrespect to the ratio of width to depth of the metal section rolledtherein.

Thus, when reducing a metal section by means of the method and rollingmill of the present invention, the section is passed longitudinallybackwards and forwards through the rolls without being moved laterallyand without being turned about its longitudinal axis between the passes.The working rolls act on said second sides or edge sides of the metalsection being reduced and are normally screwed down between each pass.The guide rolls arranged on each side of the working rolls have asmooth, cylindrical barrel and the guide rolls are permanently adjustedwith respect to the metal section in question, i.e. the nip of the guiderolls is constant and identical for both guide roll pairs during theentire rolling operation.

The guide rolls, which preferably are driven, serve, among other things,to maintain the correct position of the metal section being reduced forentry into the working roll nip and to guide the section during therolling operation and to counteract widening of the metal section duringthe reduction process, thereby maintaining the distance between thefirst or originally the broadest sides of the metal section. Thus, theguide rolls form effective guide means and replace the guides andoperating bars used with conventional rolling mills. The working rollsmay have a smooth barrel surface, although each of the rolls is normallyand preferably provided with a groove having a width corresponding tothe width of the edge sides of the metal section to be reduced. Thegroove, however, is shallow and preferably has a depth of at most onethird the width of the edge sides of the metal section to be reduced,and hence the effective guidance afforded by the guide rolls is requiredwhen feeding the metal section between the nip of the working rolls andwhile reducing said metal section between said rolls, in order toprevent the metal section being reduced from becoming misaligned ordeformed, as a result of the metal section climbing over the edges ofshallow grooves arranged in the working rolls during the rollingoperation.

The roller paths located in front of and behind the rolling mill of thepresent invention may be of very narrow construction, and when usinghorizontal working rolls and vertical guide rolls, as is preferred, therollers of the roller paths may be provided with grooves to effectivelysupport the metal section being reduced, since the width of the metalsection being reduced is constant during the entire rolling operation.Owing to the effective guide effect obtained by the guide rolls, therollers of the roll paths may, if the guide rolls are driven as ispreferred according to the invention be freely rotatable or may befreely rotatable during the actual rolling operation and arranged to bedriven substantially only when feeding the metal section to be reducedto the rolling mill or removing the finally reduced metal sectiontherefrom.

If the amount by which the section is reduced on each pass isexcessively small, a decrease in width is obtained at the center portionof the section, which means that this portion of the section is notsurface worked by the pair of guide rolls, thereby incurring the risk ofsurface faults. This risk can be eliminated and the capacity of therolling mill increased by using, in accordance with the invention,working rolls having a diameter which is at least 0.8 times the originalheight or depth of the section and a greater reduction is made per pass,suitably a reduction of the order of 0.080. l 2 times the diameter ofthe working rolls.

In order to obtain the desired guiding effect of the guide rolls, theguide rolls should be located as close to the working rolls as possible.In accordance herewith it is preferred that the distance from the nipsof the guide roll pairs to the nip of the working roll pair is at most(D-l d), preferably at most 0.7 (D+d), where D is equal to the diameterof the working rolls and d is equal to the diameter of the rolls of theguide roll pair in question. Further, the diameter of the guide rolls issuitably only about 0.25-0.50 times that of the working rolls.

Although the invention is not restricted thereto, a metal section havinga width relationship between the broad side and the edge side of a ratioin the range of 2:1 to 5:1 and preferably 3:1 to 4:1, can be reducedpreferably by means of the apparatus and method of the invention.Without being turned around its long axis, the metal section can bereduced to such an extent by means of the working rolls that the metalsection obtains a width relationship between the original broad side andedge side of 0.2-1 .0, wherewith the metal section is lengthened from 2to 25 times its original length, and a width relationship of 025-033,whereby the metal section is lengthened from 6 to 20 times its originallength. For example, a continuously cast metal section whose broad sidesare 300 mm in width and whose edge sides are mm in width can be reducedto such an extent while utilizing the same barrel region of the workingrolls that, while constantly maintained the width of the edge sides, theoriginal broad side obtains a width of 27 mm. The rolled section canthen be charged directly to a continuously operating finishing rollingmill.

The invention will now be described in more detail with reference to anembodiment of the novel rolling mill illustrated in the accompanyingdrawing, in which:

FIG. 1 is a perspective and diagrammatically view of the working rollpair and guide roll pairs of a rolling mill constructed in accordancewith the invention, and also illustrates portions of two roller conveyorpaths connected to both sides of the rolling mill and a metal sectionbeing reduced in the mill, portions of one working roll being cut awayto enable the construction of the roll to be seen more clearly.

FIG. 2 is a front view of the working rolls illustrated in FIG. 1, andshows the rolls subsequent to the metal section having been finallyreduced therebetween.

FIG. 3 is a diagrammatic and perspective view of the rolling millaccording to the invention and shows the arrangement of the workingrolls and guide rolls in a common frame structure, of which structureportions have been cut away to illustrate the construction more clearly.

In FIGS. 1-3, the reference numerals 10 and 11 indicate the upper andlower rolls of a pair of horizontally extending working rolls. Theworking rolls 10, 11 are arranged between two pairs of verticallyextending guide rolls located close to said working rolls, one pair ofguide rolls being shown at 12 and the other at 13. It will beunderstood, however, that the invention is not restricted to theillustrated orientation of the working rolls and guide rolls, but thatthe working rolls may extend vertically or be inclined to the horizontalplane and that the guide rolls may extend horizontally or be displacedto an angle of 90 relative to the working rolls when seen in the rollingdirection. FIG. 3 illustrates the working and guide rolls mounted in acommon frame structure, comprising an intermediate frame 14, in whichthe working rolls 10, 11 are journalled for rotation and for movementtowards and away from each other, and two outer frames 15, 16, in whichthe guide rolls 12 and 13 are mounted for rotation. In the illustratedembodiment, the frames are joined together to form a frame structure orstand by means of bolts 17.

The working rolls 10, 11 have radial bearings 18 and axial bearings 19,which are housed in bearing housings 20 and 21. The bearing housings 21,of which only one is shown in FIG. 3, are stationarily mounted in theframe 14 and accomodate the bearings 18, 19 of the lower and thusstationary working roll 11, while the bearing housings for the bearings18, 19 of the upper working roll are connected with or form a portion ofa yoke structure 22, which is mounted for vertical movement in the frame14 and arranged to be dis placed upwards and downwards for the purposeof varying the size of the nip of the working rolls and for screwingdown the upper working roll' 10, by means of a hydraulic motor shown at23. The working rolls 10, 11, are provided at one end thereof withdriven trunnions 24, intended to be connected in a conventional mannerto a reversible drive motor (not shown) via a drive spindle 25 (FIG. 3).

Similarly to the lower working roll 11, the vertical guide rolls 12 and13 are also journalled radially and axially in bearing housings 26 inrespective frames and 16. Only three bearing housings 26 for the rolls12 are shown in the frame 15 in the drawing. The bearing housings notshown in the drawing for the rolls 13, however, are arranged in the samemanner as the bearing housings for the guide rolls 12. The bearinghousings 26 are arranged to be stationary, but are supported laterallyby means of wedges 27, which in turn bear against the inside of thevertical portions of the associated frame, and by means of exchangeabledistance means 28, so that adjustment of re-setting of the bearinghousings and therewith the nip of the guide rolls is made possible, forexample to permit such adjustment to be made after grinding the barrelsurface of the guide rolls I2, 13 or when it is desired to adjust therolling mill in respect of metal sections 29 having a different width ofthe edge side 30.

Similarly to the working rolls 10, 11, the guide rolls 12, 13 areprovided with trunnions 31 which are driven in a conventional manner,via spindles 32, by one or more reversible motors 33. As will be seen,the illustrated drive arrangement is shown in extremely simplified form.The arrangements required to drive sequentially arranged rolls atdifferent speeds are, however, known to those skilled in the art, andalthough such arrangements form part of the novel rolling mill they donot constitute part of the present invention and are not thereforedisclosed in detail.

As indicated by the rollers 34 in FIG. 1, roller paths are arranged onboth sides of the rolling mill for conveying the metal section 29 to therolling mill and the finally rolled metal section 35 (FIG. 2) awaytherefrom.

Although when used for reducing certain metal materials the workingrolls 10, 11 may have a smooth barrel surface, it is mostly toadvantage, and in a number of cases necessary, that the rolls areprovided with shallow grooves 36, as illustrated in the drawing, thegrooves 36 being located exactly in register with the nips of the guideroll pairs and have a width which is equal to the width of said nips.Although the grooves 36 are rectangular in the illustrated embodiment,they may, in accordance with the invention, be at least slightlyrounded.

When using the rolling mill of the present invention, a metal section 29to be reduced and the width of the edge sides 30 of which coincide withthe permanently adjusted width of the nips of the guide rolls can beconveyed by means of the rollers 34 to one side of the rolling mill,where the metal section is engaged, for example, by the guide rolls 12and fed to the working rolls l0, 11, the width of the nip of which hasbeen adjusted so as to be slightly less than the width of the broadsides 37 of the metal section to be reduced. The distance be tween theradial bearings 18 of the working rolls should therewith be as short aspossible, suitably at most twice the smallest width of the metal section29. In this respect, the diameter of each working roll 10 or 11 shouldbe substantially equal to or greater than the height or depth of thehighest metal section 29 to be rolled down in the rolling mill, therebyobtaining satisfactory working of the metal section throughout itsheight while at the same time a high degree of reduction can be had witheach pass and local spreading so-called dog bone profile can besubstantially avoided. The metal section 29 being reduced is engaged onthe exit side of the working rolls by the guide rolls 13, which reducethe section to its original width in those instances when the width ofthe section has been increased in the working rolls. The diameter of theguide rolls 12, 13 may suitably have a diameter in the region of about0.250.50 times the height of the highest metal section to be rolled inthe mill. In this way the surface layer of the broad sides of thesection 29 is worked in a manner such as to greatly eliminate surfacefaults in the finished section. When the end 38 of the metal section 29has passed through the working rolls 10, 11, the upper working roll 10is moved slightly downwardly and a new pass is made in the oppositedirection by reversing the drive direction of the roll 10, 11, 12 and13. Rolling is repeated in passes in the described manner, until themetal section being reduced has obtained the desired reduction,whereafter the rolled metal section 35 is removed from the rolling millby means of the rollers 34.

The invention is not restricted to the described and illustratedembodiment, but the method can be modified within the scope of thefollowing claims.

What is claimed is:

1. A method for producing a semi-finished metal section from anelongated piece of stock of rectangular cross section having twoopposing first sides of greater width than the remaining two secondsides, said method comprising:

a. passing the stock between two working rolls contacting the secondsides, said working rolls having a diameter of at least 0.8 times thewidth of said first sides and being mounted for adjustable movementtoward each other, and two pairs of guide rolls positioned on eitherside of the working rolls and contacting the first sides, said guiderolls having a smaller diameter than the working rolls and presenting anip of constant width therebetween;

b. reversing the direction of movement of the stock and again passing itbetween the rolls without turning the stock around its longitudinalaxis;

c. guiding the stock into and out of the roll nip during successivepasses;

d. adjusting the working rolls during successive passes to bear againstthe second sides and to reduce the width of the first sides whilemaintaining a constant width between the guide rolls.

2. The method of claim 11 including the step of using a metal stockhaving a width relationship between said first and said second sides of2:1 to 5:1.

3. The method of claim 1 including the step of reducing the metal stockby means of said working rolls to a width relationship between saidfirst and said second sides of 1:5 to 1:1, whereby the metal stock isextended to 2-25 times its original length.

4. The rolling method of claim 1 including the use of working rollshaving smooth barrel surfaces.

5. The method of claim 1 including the use of working rolls havingshallow grooves, the width of which corresponds to the width of saidsecond sides of the metal stock to be reduced and a depth which at mostis one third of the width of said second sides of the metal stock.

6. The method of claim 1 including the step of using guide rolls havinga diameter of from 0.25-0.50 times the diameter of the working rolls.

1. A method for producing a semi-finished metal section from anelongated piece of stock of rectangular cross section having twoopposing first sides of greater width than the remaining two secondsides, said method comprising: a. passing the stock between two workingrolls contacting the second sides, said working rolls having a diameterof at least 0.8 times the width of said first sides and being mountedfor adjustable movement toward each other, and two pairs of guide rollspositioned on either side of the working rolls and contacting the firstsides, said guide rolls having a smaller diameter than the working rollsand presenting a nip of constant width therebetween; b. reversing thedirection of movement of the stock and again passing it between therolls without turning the stock around its longitudinal axis; c. guidingthe stock into and out of the roll nip during successive passes; d.adjusting the working rolls during successive passes to bear against thesecond sides and to reduce the width of the first sides whilemaintaining a constant width between the guide rolls.
 2. The method ofclaim 1 including the step of using a metal stock having a widthrelationship between said first and said second sides of 2:1 to 5:1. 3.The method of claim 1 including the step of reducing the metal stock bymeans of said working rolls to a width relationship between said firstand said second sides of 1:5 to 1:1, whereby the metal stock is extendedto 2-25 times its original length.
 4. The rolling method of claim 1including the use of working rolls having smooth barrel surfaces.
 5. Themethod of claim 1 including the use of working rolls having shallowgrooves, the width of which corresponds to the width of said secondsides of the metal stock to be reduced and a depth which at most is onethird of the width of said second sides of the metal stock.
 6. Themethod of claim 1 including the step of using guide rolls having adiameter of from 0.25-0.50 times the diameter of the working rolls.